FR2655037A1 - Process for the manufacture of light aggregates and products obtained - Google Patents

Abstract

Light aggregates are obtained by coating beads of expanded polymer (such as for example polymer) with the aid of a basic aqueous emulsion containing 50-65 % (by weight) of bitumen permitting mixing at ordinary temperature. The coated granulates obtained are then dried by mixing with a fine pulverulent material such as, for example, ground limestone, cement or sand. Mixtures are obtained which are stable in storage and to moisture, capable of being transported and delivered in bulk and capable of being used for many applications, depending on the quantities of pulverulent material employed: slabs and insulating panels, lightweight concretes, materials of construction.

Description

 The present invention relates to the field of microporous light materials and especially relates to a process for the manufacture of light aggregates based on expanded polymers in the form of pellets or beads which have undergone an appropriate treatment: It also relates to the products thus obtained, suitable for being stored and transported in bulk and usable as insulating products and as construction materials, by incorporation of fillers, for example for making light-weight concretes.

 It has already been attempted or recommended for a long time to incorporate expanded resins or polymers, in the case where they are reduced to the form of spherical or ball granules, in compositions of the light concrete type intended for construction, with a view to imparting to the latter final characteristics of porosity, sound insulation or other and to facilitate handling.

 To achieve such incorporation of light aggregates in the constituent products of a mortar or concrete, such as sand, cements or the like, it is necessary to choose an appropriate binder capable of perfectly coating the polymer beads without causing chemical attack. nor of physical deformation and which is moreover compatible with the constituents subsequently added for the confection of building materials.

Various binders have been recommended for this purpose such as substances of a protein nature such as collagen, animal blood (patent FR published No. 2574 068) or else
bitumen (Dutch patent N "71.13658, European patent N" 31365) either alone or with added sodium silicate. In these latter patents, the coating with bitumen is done hot, at a temperature of at least 40 "C and, although the composition of the bitumen is not specified, it may be thought that these must be the products 80/100 type classics which are hot binders and which, in fact, are not satisfactory for the coating of expanded plastics. It is undoubtedly for this reason, moreover, that the aforementioned patents n were not kept in force and a commercial exploitation could not be born.

An interesting solution has now been found to the problem of obtaining light aggregates by coating expanded plastics with a bituminous binder, this thanks to the use of a so-called binder.
cold "allowing perfect coating of plastic particles at ordinary temperature without the phenomenon of physical deformation of the latter and with perfect chemical harmlessness.

 In accordance with the invention, a basic aqueous emulsion with a content of 50 to 65% (by weight) of bitumen is used as binder. For example, it is advantageous to use the emulsion called "COLSOL" (COLAS company) constituted by a dispersion of fine bitumen particles (in particular 180/200) in water to which an emulsifier has been added, such as for example an alkaline amino acid salt of high molecular weight as well as a small amount of a preservative. Such a dispersion or emulsion is miscible with batten in all proportions, its ENGLER cosiness screw is of the order of 8 to 12 "and the bitumen contents are often between 57 and 60% (in pots).

However, any alkaline and over-stabilized bituminous emulsion (that is to say stable during storage and / or transport) can be used in the context of the invention.

 According to the general definition of the process of the invention, the beads of expanded polymer, of density 10 to 15 kg / m3, are impregnated at ordinary temperature, using the basic aqueous emulsion at 50-65% (weight). bitumen, in an amount of 15 to 50 liters per m3 of ball, then the coated aggregates are dried by contacting with a fine pulverulent material chosen from the group: limestone powder, sand, cement (or equivalent materials); the aggregates obtained, perfectly stable in storage and in humidity, which can be transported and delivered in bulk.

 In practice, the quantity of pulverulent material necessary for drying is generally double by weight, that of the bituminous emulsion for coating the beads.

For example, if 20 liters of 55% bitumen emulsion is used, approximately 4 kg of cement will be used. In this case, given the density of approximately 13 kg / m3 of the balls (in the case of polystyrene), a product of mass 50 kg / m3 will be obtained. This product can be directly put in a bag and used for various uses such as making slabs and / or light walls for insulation. Of course, the above quantities may vary and are not limitative.

 According to the invention and according to a variant, the dried aggregates as described above can serve as a basis for the production of compositions suitable for other applications. For example, if we use at least ten times more cement than above, i.e. 100 to 300 kg per m3 of logs, we obtain a dry product capable of being bagged and ready for use, for example for making lightweight concrete by adding water.

 In the case, and according to another nonlimiting variant, where sand is used instead of cement, in quantities of 150 to 300 kg per initial m3 of balls, a bulk material can be obtained which can be loaded directly by excavator or loader-truck loader then delivered as is. The product obtained can be stored outside without, apparently, caking and blocking phenomenon. Applications can be multiple in the industrial field, such as in construction.

 Other applications can also be envisaged, such as for example obtaining filtering products by adding peat to the impregnated and dried aggregates.

 The mixing operations (kneading the beads of expanded plastic material (such as polymer) for example then adding dry material can be carried out in any material and according to any technique known per se, which are not an integral part of the characteristics of the material. 'invention.

Claims (1)

-CLAIMS 1. Method for obtaining light aggregates of the type comprising a coating of particles or beads of polymer expanded by a bituminous binder, characterized in that the polymer beads 3 of density are impregnated at ordinary temperature 10 to 15 kg / m3 with a basic aqueous emulsion containing 50-65% (by weight) of bitumen in an amount of 15 to 3  50 liters per m3 of ball then dries the coated aggregates  by a powdery material at the end of the group: callus powder  cairo, sand, cement; the aggregates obtained, perfectly  stable in storage and humidity, can be transported  tees and delivered in bulk.  2. Method according to claim 1, characterized  in that the quantity of said pulverulent material is 15  at 50 kg per m3 of ball.  3. Method according to any one of the claims  1 or 2, characterized in that we add to the aggregates  dried mixes additional quantities of  type sand, cement, or the like corresponding to furnaces  chettes from 100 to 300 kg per initial m3 of logs.  4. Products obtained according to any one of claims 1 to 3 and usable, in particular, as the case may be, as light insulating materials, lightweight concrete ready for use, industrial products for construction.